Design and implementation of a 6 DOF parallel manipulator with passive force control.

摘要

Parallel mechanism has been studied for several decades. It has various advantages such as high stiffness, high accuracy and high payload capacity compared to the commonly used serial mechanism. This work presents the design, analysis, and control strategy for a parallel compliance coupler for force control (PCCFC) based on a parallel platform design. The device is installed on the distal end of an industrial manipulator to regulate the contact wrench experienced when the manipulator comes into contact with objects in its environment. The parallel mechanism is comprised of a top platform and a base platform that are connected by six instrumented compliant leg connectors. The pose of the top platform relative to the base as well as the external wrench applied to the top platform is determined by measuring the displacements of the individual leg connectors. The serial robot then moves the PCCFC in order to achieve the desired contact wrench at the distal end.; A mechanical system has been fabricated with an emphasis placed on minimizing the system size and minimizing friction at the joints. Each leg has been calibrated individually off-line to determine connector properties, i.e., spring constant and free length.; The spatial compliance matrix of the PCCFC has been studied to better understand the compliant property of the passive manipulator. The forward analysis for the special 6-6 parallel platform as well as the kinematic control is also studied. The outcome of this research will advance the contact force/torque and pose regulation for in-contact operations.